Histological based sub-chronic toxicity testing of target heavy metals of crude oil spill; Using the histo-morphometry of liver of Wistar rat

This study was aimed to evaluate in histological term, the suc-chronic toxicity of some target crude oil contaminants on the histo-morphometry of the liver of exposed Wistar rats. The following target chemicals (TCs; cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb) and nickel (Ni) were selected based on findings from literature review of chemical analysis done on crude oil spill site. Thirty (30) inbred male Wistar rats of average weight 150-200g (5 for control and 25 for experimental – 5 for each of the five TC treated groups). Rats were later sacrificed and the target organ (liver) excised and used for qualitative histological evaluation. Gross anatomical assessment showed that there was no significant difference (P> 0.05) when correlating weight gain between the treated and control groups. Histological evaluation showed the following major lesions: glomerular congestion, degeneration and necrosis; tubular degeneration and necrosis; Interstitial inflammation, hemorrhage and necrosis. This study gives credence to the fact that histology-based evidence is a veritable tool for assessing sublethal level of environmental stressors in the certification of toxicity.